AstroSynthesis includes a 3D universe generator that takes into account the main physics, chemistry and astrology laws to generate a random universe that is completely consistent. You won't find stars that are too near each other, some planets will have moons and their features will make sense depending on their location.
The application also generates detailed information about each planet and celestial object, temperature, gravity effects, location of near nebula, asteroid belts... It also traces interstellar routes to travel from one planet or galaxy to another, thus making clear which route anyone would have to take from one planet to another and how long they would take.
Furthermore, its 3D view is perfect to play and move the focus so that we can always center it on the area of the universe that the PCs are moving around.
So, if you want to create your own universe of an RPG, don't think twice and download AstroSynthesis.